Crashed when block mined (!)

Can anybody shed a bit of light to the following situation?

Since starting this node 56 seconds ago:
- You have validated 0 transactions!
- You have contributed 14.1964 Sol/s on average to the network solution rate.
- You have completed 431 Equihash solver runs.
- You have mined 1 blocks!

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zcashd: wallet/wallet.cpp:773: void CWallet::DecrementNoteWitnesses(): Assertion `nWitnessCacheSize > 0' failed.
Aborted (core dumped)

What have happened?